Can anybody explain the rationale for why Ford used different sized tires for front and rear?
Front wheels steer only.
Same chassis, different bodies, bigger tire on rear of chassis for various loads.
Ford wasn't the only one. A lot of other manufacturers did the same.
I would think it was to make it easyer to steer with a smaller tire.I would think the cost of stocking and handling 2 sizes would be more than the savings
I think 30x3's were what the earlier cars used front and rear. (NRS)
Changing the rear for the T and not the front may have seemed logical at that time.
Rich,....in other words,.....just using up what was on hand, huh? I've always wondered about that too, as it doesn't make much sense and seems somewhat counter to Henry's philosophy in regard to "standardization of parts"!
That's what I would have thought too, Harold. So there is functionally, no reason NOT to have the same size on all four? I know they did that on the later years, and I have a 1915, so I just wanted to check that there is no design reason for the different sizes.
Did they or not? The Canadian T's used 30X3 1/2 from the start! Bud.
The Model T was the lowest cost reliable quality built auto in the early years.
1913 tire catalog has smooth tread at $13.10 for 3" and $19.35 for 3 1/2" tire.
So there is a cost reason for Henry too
The front end of the T was likely done with 3" tires in design, but robust enough to handle the larger tire. By later years, with balloon tires in 21", the steering cluster did have to be redesigned to 5:1 ratio.
I'm sure this is not the correct answer but all buggies and wagons had and have smaller front than rear wheels. That is to say diameter. Ford came from the buggy/wagon era.
The out side diameter of the tire is the same front or rear, 30". Tires were very expensive to make and buy so using a tire with a larger inside diameter on the less expensive to make rim saved money. They also felt that the larger cross section rear tires were viewed as having to drive and carry the car/weight.
I guess it depends on how you look at it.
Smaller wheels up front make for lighter steering and lower cost.
... or, if you prefer...
Larger wheels at rear because of the need to withstand the additional wear and tear of braking and acceleration and to provide more traction so those forces wouldn't cause excessive skidding. The additional cost was unavoidable.
Before the advent of demountable wheels, Fords did not come off the assembly line with a spare tire, so it didn't matter that the front and rear sizes didn't match.
Canadian Fords addressed the problem of on which side to mount the steering wheel by putting front doors on both sides of the car bodies, thereby avoiding the manufacture of two different configurations of the same style body. _By the same token (more or less), Canadian Flivvers had 30x3 1/2" tires all around (I don't know what date that policy began). _I suppose it could be argued that the Canadian Model T was a higher quality, more desirable car than the American version, eh?
Horse drawn vehicles have solid axles that pivot at center on a "fifth" wheel. Smaller front wheels allow for a tighter turning radius.
I've seen where some NRS Fords used 28 x 3" tires. Did some models run 30 x 3" ?
At that time, labor costs were low and material costs were high.
All Ford models before, and later in the Model T run used the same size tires all the way around. There was a rational for the smaller front tire, and as mentioned above, many manufacturers did the same for a period of time.
Here we go.....
George - Cherry HIll posted this on the thread:
For drag racing.
For Rich – wheel/tire size for the 1906-08 N,R,S, & SR cars ref: 1907-08 Ford Models at: http://www.mtfca.com/books/1907.htm and the 1908 Models at: http://www.mtfca.com/books/1908.htm and from memory . Dates and serial numbers listed are from Trent’s Early Database which is included in a digital format in “Pate’s Early Ford Automobile Encyclopedia” and also Bruce McCalley’s two CD volume “Model T Comprehensive Encyclopedia.”
The 1906 $500 Model N Runabout which started shipping mid-Jul 1906, came with 28 x 2 1/2 inch double tube tires for all wheels.
Many folks paid $50 additional to obtain the 28 x 3 inch clincher tires on the 1906 Model N Runabouts.
Later the 28 x 2 1/2 double tube tires were discontinued and only the 28 x 3 inch clincher tires were offered and that was the end of the $500 Model N as the price went up. The Model N Runabout continued with the 28 x 3 inch clincher wheels and rim the rest of the production (the last two documented Model N Runabout shipped on Nov 21, 1908 they were serial numbers 6911 & 6927. Note cars were not assembled or shipped in serial number order – the highest documented serial number that was shipped was 6928 that was shipped Sep 29, 1908).
The mostly 1907 Model R Runabout had 30 x 3 wheels and tires.
The mostly 1907-1908 Model S Runabout had 28 x 3 clincher wheels and tires.
The mostly 1908 Model S Roadster had 30 x 3 clincher wheels and tires.
I believe Ford’s major reason for the two sizes on the Model T was to save cost on the cars.
Hap l915 cut off
Thanks for that, Hap !!
As Rich said the entire front axle/wheels rotate to steer the horse drawn wagons or buggies. The smaller front wheels allowed the wheels/axle to fold back under the "bed" to almost parallel to the center pole(I've forgotten the proper name for this center pole). You need to have the front load balanced side to side!! Wonder how I know ?
That's the tongue, Lenney. Actually, few wagons or buggies would allow the axle to be turned at right angles to the bed. Often you will find an iron rub rail at the point where the wheel would touch, many had a roller. Some carriage designs had a full cut away like a goose-neck trailer hitch that would allow that much movement, but as you point out, it's not a good idea to turn your team that sharp !!
My dad's 1900 Waverley Electric a roller on each side of the frame. If you turn the tiller too far, the rubber tire rubs against the roller.
It has Ackerman steering, like a Model T Ford (drag link, tie rod and spindle arms), not pivot steering like a typical horse drawn wagon.
See photo below - look for the two small yellow arrows.
Erik, yup ! Horse drawn refinement ! After all, it IS a horseless carriage !! (And that one looks like a perfect beauty from that detail shot ! )
We went to the Amish bulk food stores this morning and while we saw a lot of buggies i have never seen a buggy with a team pulling it! A tongue is for a team,but when using a single horse you would have Fills! Yes the Canadian model T's were 30x3.5 from the start! Bud in Wheeler,Mi.
Maybe it was a local thing, around here, spring wagons, buggies and cutters were commonly outfitted with a quick-change coupling to switch between a tongue and a pair of shafts. When we had cutter races here, they always drove teams. The term for the single horse shafts is "thills". Easy to see how they'd be called "fills". Another regionalism. That term was seldom used in this part of the country.
Oliver Wendell Holmes' poem "The Deacon's Masterpiece" or "The Wonderful One-hoss Shay" is an interesting primer on wood technology for vehicles, and rather poignant for Model Ts at the century mark. I hope we fare better than that!
Rich B., I think Lenney was referring to the "coupling pole", the pole that connects the front axle to the rear axle. That's what the wheels would hit if turned too far. Dave
David, it would depend on the vehicle. Most cases the wheel would hit the wagon box or carriage body first. On light vehicles they're called "reaches".
My 2 cents.
Unfortunately all of the people who were witness to the decision making process and could give a definitive answer passed long ago. So, like archaeologists we are left to speculate and share our opinions.
Certainly Ford was the most cost driven auto manufacturer back then so it is easy, and most of the time correct to just default to cost as the basis for the design elements of the Model T. But think about it, the labor to make the two size tires would have been virtually the same, so the only cost savings would be the reduced amount of rubber and cotton cord needed to make the smaller front tire. Weigh the two sizes and tell us the difference. I would be surprised if it amounted to as much as 5%. Tires are to this day one of the most labor intensive components of a car, so that small difference in material needed would have been insignificant in my opinion.
I think the newspaper clippings Rob posted tell the tale. Think about how common punctures and blowouts were back then. The roads would have been littered with horseshoe nails since the roads were still being shared between the two modes of transport. Furthermore, look at the list of cars and their tire sizes. Do you think Packard and Peerless would risk their reputations to save a few cents? I highly doubt it. I think safety, whether real or perceived was the driver.